Window self-detection

ABSTRACT

An apparatus for intraoral scanning includes an elongate handheld wand comprising a probe at a distal end of the handheld wand, one or more light projectors coupled to the handheld wand, and one or more cameras coupled to the handheld wand. Each camera comprises a camera sensor and objective optics comprising one or more lenses. Each camera is configured to focus at an object focal plane that is located between 1 mm and 30 mm from the lens that is farthest from the camera sensor. The apparatus further includes a fluorescent transparent film deposited on a surface selected from the group consisting of: a window of the probe through which light exits and enters the probe, and a transparent surface that is not integral to the probe.

RELATED APPLICATIONS

This patent application claims the benefit under 35 U.S.C. § 119(e) ofU.S. Provisional Application No. 62/925,323, filed Oct. 24, 2019, whichis herein incorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to three-dimensional digitalscanners, and more particularly to intraoral three-dimensional digitalscanners.

BACKGROUND

Dental impressions of a subject's intraoral three-dimensional surface,e.g., teeth and gingiva, are used for planning dental procedures.Traditional dental impressions are made using a dental impression trayfilled with an impression material, e.g., PVS or alginate, into whichthe subject bites. The impression material then solidifies into anegative imprint of the teeth and gingiva, from which athree-dimensional model of the teeth and gingiva can be formed.

Digital dental impressions utilize intraoral scanning to generatethree-dimensional digital models of an intraoral three-dimensionalsurface of a subject. Typically, a digital intraoral scanner has awindow through which light enters and exits the scanner. For hygienicreasons, some intraoral scanners may utilize disposable sleeves thatcover the portion of the scanner that is to be placed in a subject'smouth.

SUMMARY OF THE DISCLOSURE

An intraoral scanner is provided having an elongate handheld wand, aprobe at a distal end of the wand, one or more light projectors, e.g.,structured light projectors coupled to the handheld wand, and one ormore cameras coupled to the handheld wand. Typically, a lower surface ofthe probe is a transparent surface, e.g., a window, through which lightexits and enters the probe. Additionally, a transparent surface that isnot integral to the probe, e.g., a window of a sleeve that is couplableto the probe, may be provided, such that, when coupled to the probe, thetransparent surface and the window of the probe align with one anotherand light exits and enters the probe through the transparent surface aswell as through the window of the probe.

In accordance with some applications of the present disclosure, afluorescent transparent film is deposited either on the window of theprobe or the transparent surface that is not integral to the probe. Theone or more structured light projectors emit light and the one or morecameras acquire images of the object being captured, e.g., images of theintraoral scene. The projected light also stimulates the fluorescenttransparent film to emit photons of a longer wavelength than thewavelength of the projected light. The photons emitted by thefluorescent transparent film are emitted in all directions. Thus, someof the emitted light from the fluorescent transparent film scattersbackwards towards the one or more cameras and is captured by the one ormore cameras. Color sensors in the one or more cameras may be used todifferentiate between the light reflected by the fluorescent film andthe light returning from the object being scanned.

For some applications, instead of a fluorescent transparent film beingdeposited on the window or the transparent surface, the window or thetransparent surface itself, e.g., the window of the probe, or the windowof a sleeve couplable to the probe, may be a window made of afluorescent material.

There is therefore provided, in accordance with some applications of thepresent disclosure, an apparatus for intraoral scanning, the apparatusincluding:

an elongate handheld wand including a probe at a distal end of thehandheld wand;

one or more light projectors coupled to the handheld wand;

one or more cameras coupled to the handheld wand, each camera (a)including a camera sensor and objective optics including one or morelenses, and (b) configured to focus at an object focal plane that islocated between 1 mm and 30 mm from the lens that is farthest from thecamera sensor; and a fluorescent transparent film deposited on a surfaceselected from the group consisting of: a window of the probe throughwhich light exits and enters the probe, and a transparent surface thatis not integral to the probe.

For some applications, the one or more light projectors include one ormore structured light projectors.

For some applications, the fluorescent transparent film includes a layerof fluorescent ink deposited on the selected surface.

For some applications, the fluorescent transparent film includes a layerof fluorescent polymer glued onto the selected surface.

For some applications, the layer of fluorescent polymer includes afluorescent polymer tape.

For some applications, each structured light projector includes:

(a) at least one laser diode;

(b) a beam shaping optical element; and

(c) a pattern generating optical element configured to generate adistribution of discrete unconnected spots of light at all planeslocated between 1 mm and 30 mm from the pattern generating opticalelement when the laser diode is activated to transmit light through thepattern generating optical element.

For some applications, the apparatus further includes a processorconfigured to identify fluorescence of the fluorescent transparent filmin an image captured by at least one of the cameras.

For some applications, the selected surface is the transparent surfacethat is not integral to the probe.

For some applications, the processor is configured to determine whetherthe transparent surface is present by identifying fluorescence of thefluorescent transparent film.

For some applications, the processor is configured to set a focal depthof the one or more cameras in response to identified presence of thetransparent surface.

For some applications, the transparent surface includes a sleeve shapedand sized to be placed over the probe.

For some applications, the sleeve is rotationally asymmetric, and therotational asymmetry of the sleeve is such as to assist the sleeve incorrectly being placed over the probe such that the transparent surfaceis aligned with the window of the probe.

For some applications, the probe and a distal end of the sleeve have thesame shape.

For some applications, the fluorescent transparent film includes afluorescent barcode disposed on the transparent surface, and theprocessor is configured to identify the transparent surface byidentifying the fluorescence of the fluorescent barcode.

For some applications, the processor is configured to identify that thetransparent surface has previously been used by identifying that thefluorescent barcode has previously been identified by the processor.

For some applications, the fluorescent transparent film is shaped toprovide a fluorescent identifier disposed on the transparent surface,and the processor is configured to identify the transparent surface byidentifying the fluorescence of the fluorescent identifier.

For some applications, the processor is configured to identify that thetransparent surface has previously been used, by identifying that thefluorescent identifier has previously been identified by the processor.

There is further provided, in accordance with some applications of thepresent disclosure, an apparatus for intraoral scanning, the apparatusincluding:

an elongate handheld wand including a probe at a distal end of thehandheld wand;

one or more light projectors coupled to the handheld wand;

one or more cameras coupled to the handheld wand, each camera (a)including a camera sensor and objective optics comprising one or morelenses, and (b) configured to focus at an object focal plane that islocated between 1 mm and 30 mm from the lens that is farthest from thecamera sensor; and

a transparent window made of a fluorescent material, the transparentwindow selected from the group consisting of: a window of the probethrough which light exits and enters the probe, and a window that is notintegral to the probe.

For some applications, the one or more light projectors include one ormore structured light projectors.

For some applications, the selected surface includes a fluorescent glassfilter.

For some applications, the apparatus further includes a processorconfigured to identify fluorescence of the fluorescent material in animage captured by at least one of the cameras.

For some applications, the selected window is the window that is notintegral to the probe.

For some applications, the apparatus further includes a sleeve shapedand sized to be placed over the probe, and wherein the window isdisposed in a wall of the sleeve.

For some applications, the processor is configured to determine whetherthe window is present by identifying fluorescence of the window.

For some applications, the processor is configured to set a focal depthof the one or more cameras in response to identified presence of thewindow.

There is further provided, in accordance with some applications of thepresent disclosure, an apparatus for use with an elongate handheld wandof an intraoral scanner, the apparatus including:

a sleeve shaped and sized to be placed over a probe of the handheldwand, the sleeve including:

-   -   a window through which light enters and exits the probe when the        sleeve is coupled to the probe, and    -   a fluorescent transparent film deposited on the window.

For some applications, the fluorescent transparent film includes a layerof fluorescent ink deposited on the window.

For some applications, the fluorescent transparent film includes a layerof fluorescent polymer glued onto the window.

For some applications, the layer of fluorescent polymer includes afluorescent polymer tape.

For some applications, the fluorescent transparent film includes afluorescent barcode disposed on the window.

For some applications, the fluorescent transparent film is shaped toprovide a fluorescent identifier disposed on the window.

For some applications, the sleeve is rotationally asymmetric and therotational asymmetry of the sleeve is such as to assist the sleeve incorrectly being placed over the probe.

For some applications, the probe and a distal end of the sleeve have thesame shape.

The present disclosure will be more fully understood from the followingdetailed description of applications thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an elongate handheld wand with astructured light projector and a camera disposed within a probe at adistal end of the handheld wand, in accordance with some applications ofthe present disclosure;

FIG. 2 is a schematic illustration of the structured light projector, inaccordance with some applications of the present disclosure;

FIG. 3A is a schematic illustration of a sleeve that is couplable to theprobe in accordance with some applications of the present disclosure;and

FIGS. 3B-C are isometric views of the sleeve of FIG. 3A, in accordancewith some applications of the present disclosure.

FIG. 4 illustrates an intraoral scanner 120, in accordance withembodiments of the present disclosure.

FIGS. 5A-5B illustrate operation of an intraoral scanner that includeslight sources disposed elsewhere than a distal end of a probe of theintraoral scanner, and that further includes a protective sleeve havinga window with a fluorescent material on or in at least a portion of thewindow, in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

Described herein are systems and techniques for optically detecting awindow of an intraoral scanner and/or the presence of a sleeve on anintraoral scanner. An intraoral scanner may include a probe with awindow through which incident light exits the probe and through whichreflected light enters the probe. In embodiments, the intraoral scannerdetects the presence of the window and/or the distance of the windowfrom a lens (e.g., from a lens that is farthest from a sensor) and/orcamera of the intraoral scanner using internal optics of the intraoralscanner and signal processing of a detected optical signal. At least aportion of the probe may be inserted into a sleeve, which may protectthe probe and a patient from contact between the probe and the patient'soral cavity. The sleeve may include a window through which incidentlight exits the sleeve and through which reflected light enters thesleeve. In embodiments, the intraoral scanner detects the presence ofthe sleeve and/or the distance of a window of the sleeve from a lens orcamera (e.g., from a lens that is farthest from a sensor of theintraoral scanner) using internal optics of the intraoral scanner andsignal processing of a detected optical signal. For example, a portionof the incident light output by the probe may reflect off of the windowof the sleeve, and the light reflected off of the window of the sleevemay be processed using one or more signal processing algorithms todetect the sleeve's window and thus the presence of the sleeve.Additionally or alternatively, the sleeve (e.g., a window of the sleeve)may emit light that is captured by a sensor of the intraoral scanner andprocessed using image processing or signal processing algorithms todetect the presence of the sleeve. Accordingly, internal optics of theintraoral scanner and image processing algorithms may be used to detectthe presence or absence of a sleeve on the probe of the intraoralscanner. Additionally, in at least one embodiment the internal opticsand image processing algorithms are used to determine a uniqueidentifier (ID) of a sleeve on the probe. In at least one embodiment, atleast a portion of the sleeve's window is coated with or otherwiseincludes a fluorescent material (e.g., a fluorescent film). Lightgenerated by the intraoral scanner may cause the fluorescent material tofluoresce. The fluorescing material and thus the sleeve is then detectedbased on performing image processing or signal processing on light thathas reflected off of the fluorescing material and/or light emitted bythe fluorescing material on or in the sleeve's window.

In one embodiment, an intraoral scanner or computing device incommunication with an intraoral scanner uses image data to detect thepresence or absence of a sleeve on the intraoral scanner. In oneembodiment, the intraoral scanner generates image data, processes theimage data, and determines whether a sleeve is present or absent (e.g.,whether or not a sleeve is disposed on the intraoral scanner) based on aresult of the processing. In one embodiment, the image data that isgenerated is associated with fluorescence of a window of the sleeve. Inone embodiment, if the sleeve is not detected, the intraoral scanner orcomputing device outputs an indication that the sleeve is not presentand/or that a sleeve should be placed on the intraoral scanner. Forexample, the intraoral scanner may output an audible, tactile and/orvisual indication, such as by activating a light, outputting a soundand/or vibrating.

Reference is now made to FIG. 1, which is a schematic illustration of anelongate handheld wand 20 with a light projector 22, e.g., a structuredlight projector 22, and a camera 24 disposed within a probe 26 at adistal end 27 of handheld wand 20, in accordance with some applicationsof the present disclosure. It is noted that FIG. 1 shows only oneprojector 22 and only one camera 24 by way of example and notlimitation. For some applications, one or more structured lightprojectors 22 and one or more cameras 24 may be disposed within probe26. Each of the one or more cameras 24 typically (a) has a camera sensor28 and objective optics 30 comprising one or more lenses 32, and (b)focuses at an object focal plane 34 that is located at least 1 mm and/orless than 30 mm from the lens that is farthest from camera sensor 28. Insome embodiments, elongate handheld wand 20 further includes one or moreadditional light sources (not shown) that may not generate structuredlight. The one or more additional light sources may be coherent ornon-coherent light sources. In one embodiment, the one or moreadditional light sources are light emitting diodes. The one or moreadditional light sources may be activated at different times than thestructured light projector 22 in embodiments. For example, the one ormore additional light sources may be activated when elongate handheldwant 20 is first turned an and/or at the beginning of the scanningprocedure before scans are generated, and the one or more structuredlight projectors 22 may be activated when scans are to be generated.

Reference is now made to FIG. 2, which is a schematic illustration ofstructured light projector 22, in accordance with some applications ofthe present disclosure. Typically, each structured light projector 22comprises (a) at least one laser diode 52, (b) a beam shaping opticalelement 54, and (c) a pattern generating optical element 56, whichgenerates a distribution of discrete unconnected spots of light at allplanes, e.g., object focal plane 34, located at least 1 mm and/or lessthan 30 mm from pattern generating optical element 56 when laser diode52 is activated to transmit light through pattern generating opticalelement 56.

Reference is again made to FIG. 1. Typically, a lower surface of probe26 is a transparent surface, e.g., a window 38, through which lightexits and enters probe 26. Additionally, a transparent surface 40 thatis not integral to probe 26, e.g., a window of a sleeve that iscouplable to probe 26, may be provided, further described hereinbelowwith reference to FIGS. 3A-C. The window of the sleeve and/or window 38of the probe may be composed of any suitable transparent material, suchas glass, plastic, quartz, and/or other material. When coupled to probe26, transparent surface 40 and window 38 of probe 26 align with oneanother such that light exits and enters probe 26 through transparentsurface 40 that is not integral to probe 26 as well as through window 38of probe 26.

In accordance with some applications of the present disclosure, afluorescent transparent film 36 is deposited either on window 38 ofprobe 26 or on transparent surface 40. Arrows 42 schematically representlight projected by one or more structured light projectors 22. Arrow 44schematically represents the projected light reflecting off of an object46, e.g., intraoral surface, being scanned, e.g., a three-dimensionalintraoral surface, and entering one or more cameras 24, such that one ormore cameras 24 acquire images of the object being scanned, e.g., of theintraoral scene. In some embodiments, the light projected by one or morestructured light projectors 22 also stimulates fluorescent transparentfilm 36 to emit photons of a longer wavelength than the wavelength ofthe projected light. Typically, fluorescent transparent film 36 is tunedto emit photons of a predetermined wavelength, e.g., at least 520 nmand/or less than 680 nm, or at least 410 nm and/or less than 700 nm, orwithin the visible spectrum of light. This is based on a phenomenonknown as Stokes shift, whereby the illumination photons are absorbed bythe molecules in the fluorescent layer, which then enter an excitedstate. As the excited molecules relax, they emit photons which have lessenergy than the absorbed photons, resulting in an emission of photons oflonger wavelength than the illumination photons. The optical system ofhandheld wand 20 may include one or more filters and/or other opticalcomponents, which may filter out one or more wavelengths of light. Theselection of such filters in the optical system may be influenced by thewavelengths of light that excite fluorescent layer and/or by thewavelengths of light emitted by fluorescent layer. In embodiments,fluorescent material choice influences optical part selection for thehandheld wand.

The fluorescent layer, filters and/or light sources (e.g., structuredlight projectors and/or additional light sources) may be selected towork together. For example, if the structured light projectors are toexcite the fluorescent layer, then the structured light projectors andfluorescent layer may be selected such that wavelengths output by thestructured light projectors output light that causes the fluorescentmaterial to fluoresce. If the one or more additional light projectorsare to excite the fluorescent layer, then the structured lightprojectors and fluorescent layer may be selected such that the lightoutput by the structured light projectors does not cause the fluorescentlayer to fluoresce, and the one or more additional light sources may beselected such that a wavelength of light output by the one or moreadditional light projectors does cause the fluorescent layer tofluoresce. Additionally, the filters may be selected such that they donot filter out wavelengths of light that cause the fluorescent filter tofluoresce and/or wavelengths of light emitted by the fluorescent layer.

Fluorescent transparent film 36 may be tuned to emit photons of apredetermined wavelength, e.g., at least 520 nm and/or less than 680 nm,or at least 410 nm and/or less than 700 nm, or within the visiblespectrum of light. Some examples of fluorescent material that may beused for the fluorescent layer include Alexa Fluor® 405, which has amaximum absorbance of around 401 nm and a maximum emission of around 421nm, Alexa Fluor® 488, which has a maximum absorbance of around 495 nmand a maximum emission of around 519 nm, Alexa Fluor® 647, which has amaximum absorbance of around 650 nm and a maximum emission of around 665nm, Alexa Fluor® 700, which has a maximum absorbance of around 702 nmand a maximum emission of around 723 nm, APC, which has a maximumabsorbance of around 650 nm and a maximum emission of around 661 nm,Cy5, which has a maximum absorbance of around 649 nm and a maximumemission of around 670 nm, DyLight® 405, which has a maximum absorbanceof around 400 nm and a maximum emission of around 420 nm, DyLight® 488,which has a maximum absorbance of around 493 nm and a maximum emissionof around 518 nm, DyLight® 549, which has a maximum absorbance of around562 nm and a maximum emission of around 576 nm, DyLight® 649, which hasa maximum absorbance of around 654 nm and a maximum emission of around673 nm, DyLight® 680, which has a maximum absorbance of around 692 nmand a maximum emission of around 712 nm, DyLight® 750, which has amaximum absorbance of around 752 nm and a maximum emission of around 778nm, DyLight® 800, which has a maximum absorbance of around 777 nm and amaximum emission of around 794 nm, FITC, which has a maximum absorbanceof around 490 nm and a maximum emission of around 525 nm, Pacific Blue™,which has a maximum absorbance of around 410 nm and a maximum emissionof around 455 nm, PerCP, which has a maximum absorbance of around 490 nmand a maximum emission of around 675 nm, PE, which has a maximumabsorbance of around 490 or 565 nm and a maximum emission of around 578nm, Texas Red®, which has a maximum absorbance of around 596 nm and amaximum emission of around 615 nm, and TRITC, which has a maximumabsorbance of around 596 nm and a maximum emission of around 570 nm.These are merely examples of fluorescent materials, and any other typesof fluorescent materials may also be used.

In some embodiments, elongate handheld wand 20 further includes the oneor more additional light sources mentioned above, and the one or moreadditional light sources emit light that causes the fluorescenttransparent film 36 to fluoresce and therefore to emit photons of thelonger wavelength than the wavelength of the projected light beingabsorbed by the fluorescent transparent film 36.

For some applications fluorescent transparent film 36 is a layer offluorescent ink, e.g., a fluorescent material mixed in a polymericsolution, deposited on window 38 of probe 26, or on transparent surface40. Alternatively, for some applications fluorescent transparent film 36may be a layer of fluorescent polymer glued onto window 38 of probe 26or onto transparent surface 40. For some applications, the fluorescentpolymer may be a fluorescent polymer tape. In some embodiments, thewindow 38 of probe 26 and/or transparent surface 40 is doped with afluorescent material instead of or in addition to there being afluorescent layer or film disposed on the transparent surface 40 and/orwindow 38.

In some embodiments, some of the emitted light 48 from the fluorescenttransparent film scatters backwards towards the one or more cameras 24and is captured by camera sensor 28 along with the structured light fromone or more structured light projectors 22 reflecting off the objectbeing scanned. In some embodiments, in which the one or more additionallight sources were used to excite the fluorescent transparent film, someof the emitted light 48 from the fluorescent transparent film scattersbackwards towards the one or more cameras 24 and is captured by camerasensor 28, possibly along with the unstructured light from the one ormore additional light sources reflecting off an object and/or off of thewindow or transparent surface 40. For some applications, structuredlight projector 22 and/or the one or more additional light sourcesprojects light of a specific wavelength, and fluorescent transparentfilm 36 is tuned to emit light at a wavelength of a different wavelengththan projected light 42. Camera sensor 28, which is typically, but notnecessarily, a color sensor, captures (a) reflected light 44 reflectingoff the object being scanned and (b) emitted light 48 from fluorescenttransparent film 36. A processor 50 is used to process the capturedimages and to identify fluorescence of fluorescent transparent film 36in an image captured by at least one of one or more cameras 24, bydifferentiating between emitted light 48 emitted by transparentfluorescent film 36 and the returned optical image from reflected light44, which may be light returning from object 46 being scanned, based oncolor in the captured image.

For some applications, processor 50 may run a 3-dimensional imagereconstruction algorithm based on structured projected light 42 andreflected light 44 returning from object 46 being scanned. Emitted light48 emitted by transparent fluorescent film 36, differing in color fromreflected light 44, as described hereinabove, allows processor 50 toeasily exclude emitted light 48 from the 3-dimensional imagereconstruction algorithm. If the one or more additional light sourcesare used to emit light that excites the fluorescent film, then the lightprojected by structured light projectors 22 may have a wavelength thatdoes not cause the fluorescent film to fluoresce (e.g., does not excitethe fluorescent film).

For some applications, at least one or more projectors 22 may projectbroadband light onto object 46 being scanned, in order for cameras 24 tocapture a 2-dimensional color-image of object 46. In this case, thewavelength of emitted light 48 emitted by transparent fluorescent film36 may be the same, or similar, as a wavelength in the capturedcolor-image. The inventors have realized two ways of ensuring thatprocessor 50 can differentiate between emitted light 48 and the returnedoptical image. The first is to capture the 2-dimensional color-imageusing broadband light that is shifted towards the short-wavelength endof the color spectrum, e.g., toward the violet end of the spectrum, suchthat emitted light 48 emitted by transparent fluorescent film 36 has alonger wavelength than any of the wavelengths in the shifted broadbandlight. Processor 50 can thus identify the fluorescence based on color,as described hereinabove. Alternatively or additionally, transparentfluorescent film 36 may be shaped to define a distinct form that is notgenerally found in nature, e.g., a distinct shape, a series of lettersor digits, a barcode, or a unique identifier. Thus, even if thewavelength of emitted light 48 is the same, or similar, as a wavelengthin the color image, emitted light 48 will have a distinct form in thecolor-image and can thus be identified by processor 50. Alternatively,or additionally, if the one or more additional light projectors are usedto excite the fluorescent film, then the fluorescent film may beselected such that it does not fluoresce based on any of the wavelengthsof light in the broadband light output by the at least one or moreprojectors 22.

In one embodiment, elongate handheld wand 20 may alternate betweenpowering on structured light projectors 22 and/or the one or moreadditional light projectors. In some embodiments, the one or moreadditional light source is powered on at a beginning of scanning, suchas when elongate handheld wand 20 is activated, to detect the presenceor absence of a sleeve thereon. During scanning, elongate handheld wand20 may alternate between use of structured light projectors 22 and oneor more additional light sources. Structured light emitted by thestructured light projector 22 passes through window and the fluorescentfilm without causing the fluorescent film to fluoresce. Thus, thefluorescent film does not negatively impact an ability of elongatehandheld wand 20 to accurately scan intraoral objects. Light emitted bythe one or more additional light sources, on the other hand, causefluorescent film to fluoresce and emit light.

Reference is now made to FIG. 3A, which is a schematic illustration of asleeve 58 that is couplable to probe 26 in accordance with someapplications of the present disclosure. For some applications, sleeve 58is sized and shaped to be placed over probe 26 of handheld wand 20.Typically, sleeve 58 is rotationally asymmetrical, which assists apractitioner to correctly place sleeve 58 over probe 26 such thattransparent surface 40, e.g., a window 60 of sleeve 58, is aligned withwindow 38 of probe 26. Typically, but not necessarily, probe 26 and adistal end 65 of sleeve 58 have the same shape.

As described hereinabove, transparent surface 40 that is not integral toprobe 26 may be window 60 of sleeve 58, through which light enters andexits probe 26 when sleeve 58 is coupled to probe 26. Fluorescenttransparent film 36 may be deposited on window 60. Fluorescenttransparent film 36 deposited on window 60 may be any of the optionslisted hereinabove with reference to FIG. 1, e.g., a layer offluorescent ink, a layer of fluorescent polymer, or a fluorescentpolymer tape. Alternatively, or additionally, window 60 may be dopedwith a fluorescent dopant rather than or in addition to having afluorescent film disposed thereon.

It is noted that handheld wand 20, including probe 26, is shown in FIG.3A in order to illustrate how sleeve 58 is coupled to probe 26. As such,handheld wand 20, including probe 26, is shown in dashed lines in FIG.3, and projector(s) 22, camera(s) 24, and processor 50 are not shown inFIG. 3A.

Reference is now made to FIGS. 3B-C, which are isometric views of sleeve58, in accordance with some applications of the present disclosure. InFIG. 3B, for illustrative purposes the sleeve is shown in the oppositeorientation to FIG. 3A, such that window 60 is visible from above. FIG.3C shows the same sleeve 58 as in FIG. 3B, but flipped such that window60 is not visible from above.

As described hereinabove, processor 50 is used to process the capturedimages and to identify fluorescence of fluorescent transparent film 36in an image captured by at least one of one or more cameras 24. For someapplications, when fluorescent transparent film 36 is deposited ontransparent surface 40, e.g., window 60 of sleeve 58, processor 50 maybe used to determine whether transparent surface 40, e.g., window 60, ispresent by identifying fluorescence of fluorescent transparent film 36.Due to hygienic reasons it may be undesirable for the probe 26 to beplaced into the mouth of a subject without the presence of sleeve 58.Thus, for some applications, if the intraoral scanner is activated andprocessor 50 does not identify the presence of sleeve 58, thepractitioner may be alerted to place a sleeve 58 on probe 26 prior toplacement of probe 26 in the subject's mouth. For example, a visualalert may appear on a display screen associated with the intraoralscanner, or an audio alert may sound.

For some applications, it may be desirable to not only determine thepresence of a sleeve 58, but to also identify a specific sleeve 58. Dueto hygienic reasons it may be undesirable to use the same sleeve formore than one patient. Additionally, or alternatively, for commercialreasons it may be desirable to identify if a sleeve 58 is from aspecific manufacturer for sleeve authentication. Thus, it is useful forprocessor 50 to identify a specific sleeve 58, and to further identifywhether specific sleeve 58 has been used by identifying whether thespecific sleeve 58 has previously been identified by processor 50. Forsome applications, fluorescent transparent film 36 may be a fluorescentbarcode 62 or may be shaped to provide a fluorescent identifier 62disposed on transparent surface 40, e.g., on window 60 of sleeve 58,that is unique to each sleeve 58. Processor 50 thus identifiestransparent surface 40, e.g., window 60 of sleeve 58, by identifying thefluorescence of fluorescent barcode 62 or fluorescent identifier 64.Processor 50 may identify that a specific sleeve 58 has previously beenused by identifying that fluorescent barcode 62 or fluorescentidentifier 64 has previously been identified by processor 50.

For some applications fluorescent barcode 62 may include a 1-dimensionalbarcode, e.g., a Universal Product Code (UPC), which is typically astring of vertical bars that vary in thickness, or a 2-dimensionalbarcode, e.g., a Quick Response (QR) Code, a Data Matrix code, a PDF417code, or an AZTEC code. For some applications, fluorescent identifier 64may be an identifying code, such as a unique string of digits and/orletters and/or graphical representations.

For some applications, it may be desirable for processor 50 to determinea position of sleeve 58 with respect to one or more cameras 24 whensleeve 58 is coupled to probe 26, e.g., the distance between one or morecameras 24 and window 60. Processor 50 is able to determine the positionof sleeve 58 by identifying fluorescence of fluorescent transparent film36 on transparent surface 40, e.g., on window 60 of sleeve 58. One ormore cameras 24 may have a variety of possible focal depths, andprocessor 50 may set a specific focal depth of one or more cameras 24 inresponse to the identified position of external transparent surface 40,e.g., window 60 of sleeve 58. For some applications, the intraoralscanner may utilize confocal scanning to perform 3-dimensional imagingin a patient's mouth. In response to the determination of the positionof sleeve 58 with respect to one or more cameras 24, processor 50 mayset the position of window 60 as the zero-position on the z-axis usedfor confocal depth scanning. This allows the cameras to ignore salivathat may be present on window 60.

For some applications, fluorescent transparent film 36 may be positionedon window 60 such that processor 50 can identify if window 60 of sleeve58 is aligned with window 38 of probe 26, in response to identifyingfluorescence of fluorescent transparent film 36.

For some applications, alternatively to a fluorescent transparent filmbeing deposited on either window 38 of probe 26 or on transparentsurface 40 that is not integral to probe 26 (e.g., on window 60 ofsleeve 58), the window itself may be made of a fluorescent material,e.g., a fluorescent glass filter. An example of a fluorescent glassfilter is Edmund Optics Lumilass Fluorescent Glass Filters. In contrastto processor 50 identifying fluorescence of a transparent fluorescentfilm, in this case, processor 50 identifies fluorescence of thefluorescent material. Processor 50 may identify the presence of sleeve58 in response to identifying fluorescence of the fluorescent materialin an image captured by at least one of the cameras 24.

Embodiments have been discussed with reference to systems and methodsfor detecting a probe window and/or a presence or absence of a sleevefor an intraoral scanner having one or more cameras and one or morelight projectors at a distal end of a probe of the intraoral scanner. Itshould be understood that the embodiments discussed herein are alsoapplicable to other intraoral scanner designs, such as those in whichlight projectors and/or image sensors such as cameras are not disposedin the distal end of the probe. For example, the embodiments describedherein also apply to intraoral scanners in which light projectors and/orsensors or detectors are disposed at or near a proximal end of a probeof such intraoral scanners. Embodiments discussed herein apply, forexample, to intraoral scanners that determine depth based on adjusting afocal setting of an optical system of the intraoral scanner anddetermining focal settings at which an image is determined to beclearest and/or to have a highest intensity, such as intraoral scannerswith a confocal optics system.

FIG. 4 illustrates an intraoral scanner 120, in accordance withembodiments of the present disclosure. In one embodiment, the techniquesdescribed herein are applied to an intraoral scanner that includes asemiconductor laser unit 128 or other light source that emits light suchas a focused light beam, as represented by arrow 130. The light 130passes through a polarizer 132. Polarizer 132 polarizes the lightpassing through polarizer 132. Alternatively, polarizer 132 may beomitted in some embodiments. The light then enters into an opticexpander 134 that improves a numerical aperture of the light beam 130.In one embodiment, the light 130 passes through an illumination module138, which splits the light 130 into an array of incident light beams,represented here, for ease of illustration, by a single line.Alternatively, or additionally, the illumination module 138 may impartsome image pattern on the light. The illumination module 138 may be, forexample, a grating or a micro lens array that splits the light 130 intoan array of light beams. Alternatively, the illumination model may be acheckerboard pattern or other static or time varying pattern that causeslight passing therethrough to have the pattern. Modified light 136(e.g., patterned light and/or an array of light beams) is output by theillumination module 138.

The scanner 120 may further include a unidirectional mirror or beamsplitter (e.g., a polarizing beam splitter) 40 that passes the modifiedlight 136. A unidirectional mirror 140 allows transfer of light from thesemiconductor laser 128 or other light source through to downstreamoptics, but reflects light travelling in the opposite direction. Apolarizing beam splitter allows transfer of light having a particularpolarization and reflects light having a different (e.g., opposite)polarization. In one embodiment, the unidirectional mirror or beamsplitter 140 has a small central aperture. The small central aperturemay improve a measurement accuracy of the scanner 120. In oneembodiment, as a result of a structure of the unidirectional mirror orbeam sputter 140, the modified light will yield a light annulus on anilluminated area of an imaged object as long as the area is not infocus. Moreover, the annulus will become a completely illuminated spotor point once in focus. This ensures that a difference between measuredintensities of out-of focus points and in-focus points will be larger.

Along an optical path of the modified light after the unidirectionalmirror or beam splitter 140 are focusing optics 142 (which may or maynot be confocal imaging optics), and an endoscopic probing member 146.Additionally, a quarter wave plate may be disposed along the opticalpath after the unidirectional mirror or beam splitter 140 to introduce acertain polarization to the modified light. In some embodiments this mayensure that reflected light will not be passed through theunidirectional mirror or beam splitter 140. Focusing optics 142 mayadditionally include relay optics (not shown). Focusing optics 142 mayor may not maintain the same magnification of an image over a wide rangeof distances in the 7 direction, wherein the 7 direction is a directionof beam propagation (e.g., the 7 direction corresponds to an imagingaxis that is aligned with an optical path of the modified light 136).The relay optics enable the scanner 120 to maintain a certain numericalaperture for propagation of the modified light 136.

The endoscopic probing member 146 may include a rigid,light-transmitting medium, which may be a hollow object defining withinit a light transmission path or an object made of a light transmittingmaterial, e.g. a glass body or tube. In one embodiment, the endoscopicprobing member 146 include a prism such as a folding prism. At its end,the endoscopic probing member 146 may include a mirror of the kindensuring a total internal reflection. Thus, the mirror may direct themodified light towards a teeth segment 126 or other object. Theendoscope probing member 146 thus emits modified light 148 (e.g., anarray of light beams and/or patterned light), which impinge on tosurfaces of the teeth section 126.

The modified light 148 may be arranged in an X-Y plane, in the Cartesianframe 150, propagating along the Z axis. As the surface on which theincident light hits is an uneven surface, illuminated points 152 aredisplaced from one another along the Z axis, at different (X_(i), Y_(i))locations, Thus, while a point at one location may be in focus of theconfocal focusing optics 142, points at other locations may beout-of-focus. Therefore, the light intensity of returned light of thefocused points will be at its peak, while the light intensity at otherpoints will be off peak. Thus, for each illuminated point or area,multiple measurements of light intensity are made at different positionsalong the Z-axis. For each of such (X_(i), Y_(i)) location, thederivative of the intensity over distance (Z) may be made, with theZ_(i) yielding maximum derivative, Z₀, being the in-focus distance. Inone embodiment, the incident light from an array of light beams forms alight disk on the surface when out of focus and a complete light spotwhen in focus, Thus, the distance derivative will be larger whenapproaching in-focus position, increasing accuracy of the measurement.

The light scattered from each of the light points may include a beamtravelling initially in the Z axis along the opposite direction of theoptical path traveled by the modified light 148. Returned light 154 isreceived by the endoscope 46 and directed back through focusing optics142. In one embodiment, a returned light beam (e.g., which may be froman array of returning light beams) corresponds to one of an array ofincident light beams, Given the asymmetrical properties ofunidirectional mirror or beam splitter 140, the returned light isreflected in the direction of detection optics 160.

The detection optics 160 may include a polarizer 162 that has a plane ofpreferred polarization oriented normal to the plane polarization ofpolarizer 132. Alternatively, polarizer 132 and polarizer 162 may beomitted in some embodiments. The returned light 154 may pass throughimaging optics 164 in one embodiment. The imaging optics 164 may be oneor more lenses. Alternatively, the detection optics 160 may not includeimaging optics 164. In one embodiment, the returned light 154 furtherpasses through a matrix 166, which may be an array of pinholes.Alternatively, no matrix 166 is used in some embodiments. The returnedlight 154 is then directed onto a detector 168.

The detector 168 is an image sensor having a matrix of sensing elementseach representing a pixel of the image or scan. If matrix 166 is used,then each pixel further corresponds to one pinhole of matrix 166. In oneembodiment, the detector is a charge coupled device (CCD) sensor, in oneembodiment, the detector is a complementary metal-oxide semiconductor(CMOS) type image sensor. Other types of image sensors may also be usedfor detector 168, The detector 168 detects light intensity and/or otherlight properties at each pixel.

In one embodiment, detector 168 provides data to computing device viasignal B. Thus, each light intensity measured in each of the sensingelements of the detector 168, is then captured and analyzed.

Scanner 120 further includes a control module 170 connected both tosemiconductor laser 128 or other light source and a motor 172, voicecoil or other translation mechanism. In one embodiment, control module170 is or includes a field programmable gate array (FPGA) configured toperform control operations. Motor 172 is linked to focusing optics 142for changing a focusing setting of focusing optics 142. This may adjustthe relative location of a focal surface of focusing optics 142 alongthe Z-axis (e.g., in the imaging axis). Control module 170 may inducemotor 172 to axially displace (change a location of) one or more lensesof the focusing optics 142 to change the focal depth of the focalsurface. In one embodiment, motor 172 or scanner 120 includes an encoder(not shown) that accurately measures a position of one or more lenses ofthe focusing optics 142. The encoder may include a sensor paired to ascale that encodes a linear position. The encoder may output a linearposition of the one or more lenses of the confocal focusing optics 142.The encoder may be an optical encoder, a magnetic encoder, an inductiveencoder, a capacitive encoder, an eddy current encoder, and so on, Afterreceipt of feedback that the location of the one or more lenses haschanged, control module 170 may induce laser 128 or other light sourceto generate a light pulse. Control unit 170 may additionally synchronizea computing device to receive and/or store data representative of thelight intensity from each of the sensing elements at the particularlocation of the one or more lenses (and thus of the focal depth of theimaginary non-flat focal surface) via signal A and signal B. Insubsequent sequences, the location of the one or more lenses (and thusthe focal depth) will change in the same manner and the data capturingwill continue over a wide focal range of focusing optics 142.

A computing device may capture images responsive to receiving imagecapture commands from the control unit 170. The captured images may beassociated with a particular focusing setting (e.g., a particularlocation of one or more lenses in the focusing optics as output by theencoder). In one embodiment, the computing device then processescaptured images or scans captured over multiple different focusingsettings. The computing device may determine the relative intensity ineach pixel over the entire range of focal settings of focusing optics142 from received image data. Once a certain light point associated witha particular pixel is in focus, the measured intensity will be maximalfor that pixel, Thus, by determining the Z_(i) corresponding to themaximal light intensity or by determining the maximum displacementderivative of the light intensity, for each pixel, the relative positionof each point of light along the Z axis can be determined for eachpixel. Thus, data representative of the three-dimensional pattern of asurface in the teeth segment 26 or other three dimensional object can beobtained.

In at least some embodiments, scanner 120 includes a window throughwhich light exits endoscope 146 and through which returning light entersendoscope 146. In embodiments, the window includes a fluorescentmaterial therein or thereon. The fluorescent material may be, forexample, a film coated on a portion of the window or on an entirety ofthe window, as discussed herein above. Semiconductor laser 128 oranother light source of scanner 120 may cause the fluorescent materialto fluoresce, and light output by the fluorescing material may bedetected by detector 168. The detected light output by the fluorescingmaterial may be used to detect the window and/or a state of the window.

In at least some embodiments, a protective sleeve (not shown) isdisposed over a probe of the scanner 120 that includes the endoscope146. The protective sleeve may include a window that may align with awindow of the probe. The window of the protective sleeve may include afluorescent material therein or thereon instead of or in addition to thewindow of the probe. The fluorescent material on the window of theprotective sleeve may be excited by semiconductor laser 128 or anotherlight source of scanner 120, and the light output by the fluoresceningmaterial may be detected by detector 168 and used to detect a presenceof the protective sleeve and/or a state of the protective sleeve. In anexample, the light emitted by the fluorescing material may be used todetermine whether the protective sleeve is properly seated on the probe,such as by detecting a distance of one or more points of the window fromthe focusing optics and comparing the detected distance to a targetdistance. If the detected distance is different from the targetdistance, then a determination may be made that the protective sleeve isnot properly placed on the probe of the intraoral scanner 120, forexample.

FIGS. 5A-5B illustrate operation of an intraoral scanner 62 thatincludes light sources disposed elsewhere than a distal end of a probe72 of the intraoral scanner 62. As shown, probe 72 includes a protectivesleeve 74 disposed thereon. Protective sleeve 74 includes a window 76through which light enters and exits probe 72. Window 76 includes one ormore regions that include a fluorescent material. In one embodiment, thefluorescent material is a coating or film on a region of the window. Inone embodiment, a region of the window is doped with the fluorescentmaterial. In one embodiment, scanner 62 corresponds to scanner 120 ofFIG. 4.

As shown, scanner 62 includes multiple light sources 64, 65, 66, 68.Each of the light sources may be or include one or more lasers and/orlight emitting diodes (LEDs). Alternatively, other types of lightsources may be used. While four light sources are shown, other numbersof light sources may be included in scanner 62. While light sources64-68 are shown to be disposed in probe 72, they may alternatively beplaced elsewhere in the scanner 62. Light sources 64, 66 may benon-coherent light sources, such as a white light source having aparticular range of wavelengths that do not cause fluorescent material78 to fluoresce. The non-coherent light sources 64, 68 may output lightthat is used to generate color images, such as color 2D images, of animaged intraoral object. Light output by light sources 64, 66 may notcause fluorescent material 78 to fluoresce. Light source 65 may be acoherent light source that outputs light having particular wavelengththat, when it is shined on fluorescent material 78, causes fluorescentmaterial 78 to fluoresce. Light source 68 may be a coherent light sourcethat outputs light having a particular wavelength that does not causefluorescent material 78 to fluoresce. Light source 68 may emit lightthat is used to generate height maps of intraoral objects, and thus todetermine a three-dimensional surface of intraoral objects. In oneembodiment, light source 68 corresponds to semiconductor laser 128 ofFIG. 4.

Scanner 62 may alternate between powering on light source 65, lightsource 68, and/or light sources 64, 66. In some embodiments, lightsource 65 is powered on at a beginning of scanning, such as when scanner62 is activated, to detect the presence or absence of a sleeve thereon.During scanning, scanner 62 may alternate between use of light source 68and one or more light sources 64, 66. As shown, light rays 70 emitted bylight sources 64, 66 pass through window and fluorescent material 78without causing the fluorescent material 78 to fluoresce. Similarly,light emitted by light source 68 does not cause fluorescent material tofluoresce. Thus, the fluorescent material does not negatively impact anability of scanner 62 to accurately scan intraoral objects. Light rays80 emitted by light source 65, on the other hand, cause fluorescentmaterial 78 to fluoresce and emit light rays 82. The light rays 82 maybe reflected back into probe 72 and detected by a detector.

The fluorescent material 78 and one or more of the light sources 64, 66,68 may be selected such that wavelengths output by the light sources 64,66, 68 do not cause the fluorescent material to fluoresce and such thatwavelengths output by light source 65 does cause the fluorescentmaterial to fluoresce. For example, fluorescent material 78 may be tunedto emit photons of a predetermined wavelength, e.g., at least 520 nmand/or less than 680 nm, or at least 410 nm and/or less than 700 nm, orwithin the visible spectrum of light. Some examples of fluorescentmaterial that may be used include Alexa Fluor® 405, which has a maximumabsorbance of around 401 nm and a maximum emission of around 421 nm,Alexa Fluor® 488, which has a maximum absorbance of around 495 nm and amaximum emission of around 519 nm, Alexa Fluor® 647, which has a maximumabsorbance of around 650 nm and a maximum emission of around 665 nm,Alexa Fluor® 700, which has a maximum absorbance of around 702 nm and amaximum emission of around 723 nm, APC, which has a maximum absorbanceof around 650 nm and a maximum emission of around 661 nm, Cy5, which hasa maximum absorbance of around 649 nm and a maximum emission of around670 nm, DyLight® 405, which has a maximum absorbance of around 400 nmand a maximum emission of around 420 nm, DyLight® 488, which has amaximum absorbance of around 493 nm and a maximum emission of around 518nm, DyLight® 549, which has a maximum absorbance of around 562 nm and amaximum emission of around 576 nm, DyLight® 649, which has a maximumabsorbance of around 654 nm and a maximum emission of around 673 nm,DyLight® 680, which has a maximum absorbance of around 692 nm and amaximum emission of around 712 nm, DyLight® 750, which has a maximumabsorbance of around 752 nm and a maximum emission of around 778 nm,DyLight® 800, which has a maximum absorbance of around 777 nm and amaximum emission of around 794 nm, FITC, which has a maximum absorbanceof around 490 nm and a maximum emission of around 525 nm, Pacific Blue™,which has a maximum absorbance of around 410 nm and a maximum emissionof around 455 nm, PerCP, which has a maximum absorbance of around 490 nmand a maximum emission of around 675 nm, PE, which has a maximumabsorbance of around 490 or 565 nm and a maximum emission of around 578nm, Texas Red®, which has a maximum absorbance of around 596 nm and amaximum emission of around 615 nm, and TRITC, which has a maximumabsorbance of around 596 nm and a maximum emission of around 570 nm.These are merely examples of fluorescent materials, and any other typesof fluorescent materials may also be used.

It will be appreciated by persons skilled in the art that the presentdisclosure is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present disclosureincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

What is claimed is:
 1. An apparatus for intraoral scanning, theapparatus comprising: an elongate handheld wand comprising a probe at adistal end of the elongate handheld wand; one or more light projectorscoupled to the elongate handheld wand; one or more cameras coupled tothe elongate handheld wand, each camera (a) comprising a camera sensorand objective optics comprising one or more lenses, and (b) configuredto focus at an object focal plane that is located between 1 mm and 30 mmfrom the lens that is farthest from the camera sensor; and a fluorescenttransparent film deposited on a surface selected from the groupconsisting of: a window of the probe through which light exits andenters the probe, and a transparent surface that is not integral to theprobe.
 2. The apparatus according to claim 1, wherein the one or morelight projectors comprise one or more structured light projectors. 3.The apparatus according to claim 1, wherein the fluorescent transparentfilm comprises a layer of fluorescent ink deposited on the selectedsurface.
 4. The apparatus according to claim 1, wherein the fluorescenttransparent film comprises a layer of fluorescent polymer glued onto theselected surface.
 5. The apparatus according to claim 4, wherein thelayer of fluorescent polymer comprises a fluorescent polymer tape. 6.The apparatus according to claim 1, wherein each structured lightprojector comprises: (a) at least one laser diode; (b) a beam shapingoptical element; and (c) a pattern generating optical element configuredto generate a distribution of discrete unconnected spots of light at allplanes located between 1 mm and 30 mm from the pattern generatingoptical element when the laser diode is activated to transmit lightthrough the pattern generating optical element.
 7. The apparatusaccording to claim 1, wherein the apparatus further comprises aprocessor configured to identify fluorescence of the fluorescenttransparent film in an image captured by at least one of the cameras. 8.The apparatus according to claim 7, wherein the selected surface is thetransparent surface that is not integral to the probe.
 9. The apparatusaccording to claim 8, wherein the processor is configured to determinewhether the transparent surface is present by identifying fluorescenceof the fluorescent transparent film.
 10. The apparatus according toclaim 9, wherein the processor is configured to set a focal depth of theone or more cameras in response to identified presence of thetransparent surface.
 11. The apparatus according to claim 8, wherein thetransparent surface comprises a sleeve shaped and sized to be placedover the probe.
 12. The apparatus according to claim 11, wherein thesleeve is rotationally asymmetric, and wherein the rotational asymmetryof the sleeve is such as to assist the sleeve in correctly being placedover the probe such that the transparent surface is aligned with thewindow of the probe.
 13. The apparatus according to claim 11, whereinthe probe and a distal end of the sleeve have the same shape.
 14. Theapparatus according to claim 8, wherein the fluorescent transparent filmcomprises a fluorescent barcode disposed on the transparent surface, andwherein the processor is configured to identify the transparent surfaceby identifying the fluorescence of the fluorescent barcode.
 15. Theapparatus according to claim 14, wherein the processor is configured toidentify that the transparent surface has previously been used byidentifying that the fluorescent barcode has previously been identifiedby the processor.
 16. The apparatus according to claim 8, wherein thefluorescent transparent film is shaped to provide a fluorescentidentifier disposed on the transparent surface, and wherein theprocessor is configured to identify the transparent surface byidentifying the fluorescence of the fluorescent identifier.
 17. Theapparatus according to claim 16, wherein the processor is configured toidentify that the transparent surface has previously been used, byidentifying that the fluorescent identifier has previously beenidentified by the processor.
 18. Apparatus for intraoral scanning, theapparatus comprising: an elongate handheld wand comprising a probe at adistal end of the handheld wand; one or more light projectors coupled tothe handheld wand; one or more cameras coupled to the handheld wand,each camera (a) comprising a camera sensor and objective opticscomprising one or more lenses, and (b) configured to focus at an objectfocal plane that is located between 1 mm and 30 mm from the lens that isfarthest from the camera sensor; and a transparent window made of afluorescent material, the transparent window selected from the groupconsisting of: a window of the probe through which light exits andenters the probe, and a window that is not integral to the probe. 19.The apparatus according to claim 18, wherein the one or more lightprojectors comprise one or more structured light projectors.
 20. Theapparatus according to claim 18, wherein the selected surface comprisesa fluorescent glass filter.
 21. The apparatus according to claim 18,wherein the apparatus further comprises a processor configured toidentify fluorescence of the fluorescent material in an image capturedby at least one of the cameras.
 22. The apparatus according to claim 21,wherein the selected window is the window that is not integral to theprobe.
 23. The apparatus according to claim 22, further comprising asleeve shaped and sized to be placed over the probe, and wherein thewindow is disposed in a wall of the sleeve.
 24. The apparatus accordingto claim 22, wherein the processor is configured to determine whetherthe window is present by identifying fluorescence of the window.
 25. Theapparatus according to claim 24, wherein the processor is configured toset a focal depth of the one or more cameras in response to identifiedpresence of the window.
 26. Apparatus for use with an elongate handheldwand of an intraoral scanner, the apparatus comprising: a sleeve shapedand sized to be placed over a probe of the handheld wand, the sleevecomprising: a window through which light enters and exits the probe whenthe sleeve is coupled to the probe, and a fluorescent transparent filmdeposited on the window.
 27. The apparatus according to claim 26,wherein the fluorescent transparent film comprises a layer offluorescent ink deposited on the window.
 28. The apparatus according toclaim 26, wherein the fluorescent transparent film comprises a layer offluorescent polymer glued onto the window.
 29. The apparatus accordingto claim 28, wherein the layer of fluorescent polymer comprises afluorescent polymer tape.
 30. The apparatus according to claim 26,wherein the fluorescent transparent film comprises a fluorescent barcodedisposed on the window.
 31. The apparatus according to claim 26, whereinthe fluorescent transparent film is shaped to provide a fluorescentidentifier disposed on the window.
 32. The apparatus according to claim26, wherein the sleeve is rotationally asymmetric and wherein therotational asymmetry of the sleeve is such as to assist the sleeve incorrectly being placed over the probe.
 33. The apparatus according toclaim 26, wherein the probe and a distal end of the sleeve have the sameshape.